144 ON ATMOSPHERIC AND BAROMETRIC 



but instead of being at rest, the sea breeze is 

 then found blowing freely, and with increasing 

 strength. At about four in the morning the 

 gaseous pressure is represented as being again 

 at the mean, but at both these times wind is 

 blowing. Now if the theory were correct, from 

 which separate gaseous pressure is deduced, we 

 should have a calm, when the pressure was at the 

 mean ; whereas, at the times which have been 

 pointed out, of the computed mean, decided 

 winds were blowing. 



And when the air at ten in the morning is 

 found calm, we ought to presume, from the 

 existence of that fact, that an equilibrium of 

 gaseous pressure is established, such equilibrium 

 being the necessary accompaniment of a calm. 

 But the separate gaseous pressure, as that pres- 

 sure is deduced from the dew-point is very much 

 above the mean, seeing that it is at the highest 

 that it attains in the twenty-four hours. 



In like manner, at ten o'clock at night, when 

 the gases are at rest, and when therefore they 

 must be supposed to be under the influence of a 

 mean pressure, — the amount of that pressure as 

 deduced from the theory, though not so great as 



